The present invention relates to a solid-state image pickup device and a driving method thereof, and particularly to a solid-state image pickup device in which an amplifying means (column amplifier) is connected to each of vertical signal lines, and a driving method for removing noises thereof.
FIG. 1 shows one of conventional solid-state image pickup devices as disclosed in U.S. Pat. No. 5,345,266, for example. This solid-state image pickup device has such a basic construction that unit pixels 101 are two-dimensionally arranged in a matrix form and line selection is performed through vertical selection lines 103 by a vertical scan circuit 102, and also it is further constructed so that a column amplifier 105 is connected to each vertical signal line 104, a pixel signal of each unit pixel 101 is accumulated in the column amplifier 105 on a line basis, and column selection is performed by a horizontal scan circuit 106 to output the pixel signal thus accumulated through a horizontal scan signal line 107 and a sense amplifier 108.
In the conventional solid-state image pickup device thus constructed, however, the dispersion of Vth (threshold value) of every pixel of an MOS transistor constituting each unit pixel 101 is directly superposed on the output signal of the image pickup device. Since the Vth dispersion has a fixed value every pixel, a fixed pattern noise (FPN; fixed pattern noise) appears on the screen.
In order to suppress the fixed pattern noise, it has been hitherto needed that a noise removing circuit using a frame memory is provided to the outside of the device in order to store one of the output signal (noise component) under the dark condition and the output signal (picture component) under the light condition into the frame memory every pixel in advance, and the subtraction between the signal thus stored and the other pixel signal is performed to remove the noise component due to the Vth dispersion. Accordingly, a camera system must be designed in a larger size by the amount corresponding to the external mount of the noise removing circuit using the frame memory.